Transverse flash breaking in tire manufacture

ABSTRACT

A method and apparatus for alleviating the sound generated in use by tires having flash extending transversely of the tread by puncturing or penetrating and tearing the flash extending between the walls of circumferentially endless grooves in the tire tread.

United States Patent Christie et al.

[111 3,856,070 [451 Dec. 24, 1974 TRANSVERSE FLASH BREAKING IN TIREMANUFACTURE Inventors: Christopher E. Christie, Akron;

Paul E. Appleby, Cuyahoga Falls; Frank R. Tully, Hudson, all of Ohio TheGoodyear Tire & Rubber Company, Akron, Ohio Filed: Aug. 13, 1973 Appl.No.: 387,882

Assignee:

US. Cl 157/13, 83/914, 225/1 Int. Cl 82% 21/00 Field of Search 225/1,93; 83/914; 157/13 References Cited UNITED STATES PATENTS Glodde 83/914X 2,986,204 5/1961 Wilson et a1 157/13 3,763,914 10/1973 Vance 157/13Primary Examiner-Andrew R. Juhasz Assistant Examiner-Leon GildenAttorney, Agent, or Firm-F. W. Brunner; R. S. Washburn [57] ABSTRACT Amethod and apparatus for alleviating the sound generated in use by tireshaving flash extending transversely 0f the tread by puncturing orpenetrating and tearing the flash extending between the walls ofcircumferentially endless grooves in the tire tread.

1 Claim, 2 Drawing Figures FMENTEB 3,856,070

TRANSVERSE FLASH BREAKING IN TIRE MANUFACTURE The present inventionrelates to treating tires and particularly for breaking or tearing moldflash. Still more particularly, the invention relates to methods andapparatus for breaking mold flash extending transversely of thecircumferential grooves in the tread of a tire.

It is well known that small portions of rubber tend to be extruded froma two-piece mold cavity during the molding and curing of a tire and thatsuch spew, extrusion, or the like, which is commonly called mold flash,remains on the finished tire after its removal from the mold. Such flashis often considered undesirable by some persons, but is generallyobjectionable only in appearance and is not believed to produce anyundesirable effects in the operation of the tire when mounted for normaluse on a vehicle.

More recently, multipart molds for curing tires have been reintroducedin which the tire tread molding part is constructed of a plurality ofsegments which are each movable toward and away from the axis of themold. In such molds, often referred to as segmented molds, flash may beformed where pairs of segments abut. It has been found that such moldflash, which extends transversely of the tire tread and particularlythat flash which extends across otherwise continuous circumferentialgrooves tends to generate undesirable noise during operation of thevehicle on which such tire is mounted. It is an object of the inventionto diminish such noise.

The foregoing and other objects will be made apparent and the principlesof the invention will be made clear to persons skilled in the relatedarts by the following description of a presently preferred embodiment ofthe invention illustrative of what is at present believed to be the bestmode of putting the invention into practice.

The description and the annexed drawings are illustrative of theprinciples of the invention and are not to be taken as limiting thescope of the invention which is set forth in the appended claims.

In the annexed drawings:

FIG. 1 is a perspective view of an apparatus in accordance with theinvention shown in operative association with a tire; and

FIG. 2 is an enlarged view of the section 2--2 in FIG. 1.

In tires which have been molded and cured in segmented molds, treadrubber (the term being used broadly) tends to be extruded betweenadjacent pairs of segments so that there is formed a film or web offlash extending transversely of the thread, commonly in a plane parallelto the axis, such that the flash extends completely across one or moreof the circumferentially endless grooves in the non-skid pattern of thetread and at several places around the tire. This flash extendingtransversely of the tread is objected to by many persons not onlybecause of its appearance but because the uninterrupted flash isbelieved to contribute to noise and- /or vibration generated by such atire in rolling contact with a road surface on which the tire rolls.

Referring to the drawings, and particularly to FIGS. 1 and 2, a web 3 ofextruded mold flash 4 extends transversely of the tire 5 in a plane orplanes containing the tire axis 6 and extends completely across one ormore of the circumferentially endless grooves 7 formed in the non-skidportion of the tire tread 8. The web or webs 3 tend to be formed wherethe respective segments of the tread mold abut when the tire mold isclosed.

It has been found, surprisingly, that such flash 4 and particularly thewebs 3 extending between the sidewalls 9 of the grooves 7 can bepenetrated and torn, without removal of the flash from the tire andthat, by being so penetrated and tom, the noise attributed to thepresence of such flash is therebyalleviated to a considerable and usefulextent, even though no material part of the flash is actually removedfrom the tire.

In order to penetrate and to tear the flash extending transverselyacross a tread groove, a flash tearing instrument 10 is moved into agroove 7 and at least one such instrument into'each of such grooves.Relative movement between the instrument l0 and the tire 5 isconveniently effected by rotating the tire while holding the instrumentor instruments fixed relative to the tire rotation such that eachupstanding web 3 of flash within the or each groove 7 is penetrated andtorn. It is found unnecessary for the purpose to cut cleanly or toremove material from the flash.

In order to accomplish rapidly and effectively the penetration andtearing of such webs, the tearing instrument 10 is mounted resilientlyso as to move readily into the groove 7 radially of the tire andtofollow resiliently any serpentine irregularities of the groove withouttearing or scarring of the rubber of the tread elsewhere than at theparticular webs.

In order to treat rapidly and effectively each tire to penetrate, andtear open, all of the upstanding flash webs 3 in each of thecircumferential grooves 7, a plurality of penetrating and tearinginstruments 10 are mounted in a gang arrangement analogous to a commonwell known leaf rake. The individual tearing instruments 10 aresufficiently closely spaced so that at least one can resiliently enterradially into each of the respectively associated circumferentialgrooves 7 while others of the tearing instruments l0 slide upon theperipheral surface 14 or surfaces of the tread disposed between therespective pairs of grooves without any harmful effect.

In order to accomplish the aforedescribed method rapidly and effectivelyin the tire manufacturing process, the perforating and tearinginstruments 10 can be conveniently mounted in association with knownapparatus adapted to chuck and to rotate such tire about its ownrotational axis.

Referring to FIG. 1, a means 20 for mounting and rotatinga tire is shownschematically and represents, for example, a well-known white sidewallgrinding apparatus or the like upon which the tire S can be mounted,preferably inflated, and rotated in the direction indicated, arrow 21.Such mounting means can, of course, accommodate the tire 5 with its axis6 horizontal as shown, or vertically, or at any oblique angle. Aplurality of perforating and tearing instruments 10 are mountedsecurely'in an arcuate holder 22 the curvature of which approximates thetransverse profile of the crown of a tire which is to be treated. Theholder 22 is mounted to slide on a pair of parallel guide rods 24 and isconnected to the piston rod 26 of an actuating cylinder 28 the strokeaxis 30 of which lies in or closely parallel to a plane common to themid-circumferential plane of the tire and is oriented such that theholder 22 together with the plurality of tearing instruments 10 can moveIn accordance with the invention, the penetrating and tearing instrument10 itself, see particularly FIG. 2, comprises a shoe portion'32 which isfreely slidable relative to the surfaces of the tread of the tirethereby guiding the instrument so as to prevent its snagging orotherwise damaging the desired tread configuration. The shoe portion 32terminates in a second portion or tooth 34 which turns upwardly slightlyand can advantageously be thinned or sharpened so that the tooth 34cannot tear or scar the bottom or sidewalls of the groove 7 in which theinstrument operates. So long as the portion 34 is shaped to avoid damageto the desired molded surfaces of the tire, any equivalent shape cansuffice.

In order that the tearing instrument itself can resiliently enter into acircumferential groove of the tire tread, the shoe portion 32 is joinedby a U-shaped bend 36 to an elongated shank 38 which is elasticallydeflectable sufficiently to resiliently follow the tire groove 7 as thetire is rotated or to follow the road-contacting surface 14 of the treaditself between the grooves. Conveniently, the shank 38 may be integralwith the shoe portion and with the penetrating point or tooth 34 andcomprise a length of spring wire of, for example, approximately /s inchdiameter, and have a free length of approximately 6 inches. The closelyspaced plurality of tearing instruments 10 are arranged in parallelside-byside relation with the planes formed by the U-bend each orientedat least approximately normal to the crown of the tire where it isengaged by the shoe portion of the instrument.

In operation, the tire mounting and rotating means 20 is energized torotate the tire about its own normal rotation axis 6 and the holder 22together with the plurality of tearing instruments is moved forward,arrow 25, toward the tire by actuation of the cylinder 28 so that theshoe portion 32 of each of the tearing instruments 10 is urged intoslidable engagement with the tread surface sufficiently to deflect therespective elon- I gated shanks 38 by an amount approximately equivalentto the depth of the circumferential groove 7 or grooves in the tire. Oneor more of the instruments 10 in alignment with a respectivelyassociated circumferential groove 7 is or are urged by the shanks 38 tohold the shoe portion 32 thereof resiliently against the bottom of therespectively associated groove 7, while the shanks 38 aligned-with thesurfaces 14 betweenv the grooves are simply deflected so that the shoeportions 32 thereof slide harmlessly on the surfaces 14 interme-' diatethe respective grooves. As the tire is rotated, the penetrating terminalteeth 34 first pierce and then tear through the respective webs 3thereby breaking the continuity of the web 3 across the or each of therespective groove 7. The tire may be rotated one or more completerevolutions whereupon the holder 22 is retracted away from the tiretread and the operation is complete.

While certain representative embodiments and details have shown for thepurpose of illustrating the invention, it will be apparent to thoseskilled in the art that various changes and modifications may be madetherein without departing from the spirit or scope of the invention.

What is claimed is:

1. Apparatus for treating a new tire having mold flash extendingtransversely of a circumferentially endless tread groove thereincomprising means for mounting said tire rotatably, at least one flashtearing instrument capable of entering said groove, means for mountingsaid instrument formovement into said groove, and

- means for effecting relative movement between said tire and saidinstrument in a direction parallel to said groove to cause saidinstrument to penetrate and to tear said flash, the or each saidinstrument comprising 4 a spring wire hook having an elongatedelastically deflectable shank, a shoe portion slidable on a surface orsurfaces of the tread of said tire and connected to said shank by aU-shaped bend portion, and a flash penetrator terminal portion.

1. Apparatus for treating a new tire having mold flash extendingtransversely of a circumferentially endless tread groove thereincomprising means for mounting said tire rotatably, at least one flashtearing instrument capable of entering said groove, means for mountingsaid instrument for movement into said groove, and means for effectingrelative movement between said tire and said instrument in a directionparallel to said groove to cause said instrument to penetrate and totear said flash, the or each said instrument comprising a spring wirehook having an elongated elastically deflectable shank, a shoe portionslidable on a surface or surfaces of the tread of said tire andconnected to said shank by a U-shaped bend portion, and a flashpenetrator terminal portion.